1. Field of the Invention
The present invention relates to digital still camera modules, and particularly to digital still camera modules which are suitable for portable electronic devices.
2. Description of Prior Art
Currently, digital still camera modules are widely used in portable electronic devices. One trend in the ongoing development of digital still camera modules is to make them smaller and lighter in weight.
Referring to FIG. 2, a conventional digital still camera module includes a barrel 22, and a first lens 20, a filter 24, an aperture apparatus 26, a second lens 28 and an image sensor 29 set in the barrel 22 in that order from top to bottom. A top of the first lens 20 is concave, and a bottom of the first lens 20 is convex. Thus the focal length of the first lens 20 is relatively long, which requires the barrel 22 to be correspondingly long. Additionally, the space between the filter 24 and the aperture apparatus 26 also adds to the length of the barrel 22. Furthermore, the encapsulation of the image sensor 29 is by way of a PLCC (Plastic Leaded Chip Carrier). The chip which is encapsulated by the PLCC is square. Pins of the chip extend outward from around a periphery of the image sensor 29, which means that the image sensor 29 occupies additional area of a PCB (Printed Circuit Board) on which it is mounted. Moreover, the top of the image sensor 29 is covered by a glass.
With this structure, the image sensor 29 cannot adequately satisfy the requirement of high glass content, and the digital still camera module is not compact enough for many modern portable electronic devices such as mobile phones and PDAs (personal digital assistants). With price pressures growing in increasingly saturated consumer marketplaces, the digital still camera module is becoming regarded as unduly costly for installation in many portable electronic devices. Finally, the first lens 20 and the second lens 28 are spherical lenses, which have inherent spherical aberration. The spherical aberration may reduce the quality of images obtained.
An improved digital still camera module which overcomes the above-described problems is desired.